Gets or sets a value indicating whether the control should redraw its surface using a secondary buffer. The DoubleBuffered property does not affect the TreeView control. (Overrides Control.DoubleBuffered.)

Gets a value indicating whether the caller must call an invoke method when making method calls to the control because the caller is on a different thread than the one the control was created on. (Inherited from Control.)

Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control. (Inherited from Control.)

Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control. (Inherited from Control.)

Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control. Optionally, invalidates the child controls assigned to the control. (Inherited from Control.)

Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control. Optionally, invalidates the child controls assigned to the control. (Inherited from Control.)

The Nodes collection holds all the TreeNode objects that are assigned to the TreeView control. The tree nodes in this collection are referred to as the root tree nodes. Any tree node that is subsequently added to a root tree node is referred to as a child node. Because each TreeNode can contain a collection of other TreeNode objects, you might find it difficult to determine your location in the tree structure when you iterate through the collection. You can parse the TreeNode.FullPath string by using the PathSeparator string value to determine where a TreeNode label begins and ends.

You can display images next to the tree nodes by assigning an ImageList to the ImageList property and referencing the index value of an Image in the ImageList to assign that Image. Use the following properties to assign images:

Set the ImageIndex property to the index value of the Image that you want to display when a tree node is not selected.

Set the SelectedImageIndex property to the index value of the Image that you want to display when a tree node is selected.

The state images displayed in the TreeView are 16 x 16 pixels by default. Setting the ImageSize property of the StateImageList will have no effect on how the images are displayed. However, the state images are resized according to the system DPI setting when the app.config file contains the following entry:

Tree nodes can be expanded to display the next level of child tree nodes. The user can expand the TreeNode by clicking the plus-sign (+) button, if one is displayed next to the TreeNode, or you can expand the TreeNode by calling the TreeNode.Expand method. To expand all the child tree node levels in the Nodes collection, call the ExpandAll method. You can collapse the child TreeNode level by calling the TreeNode.Collapse method, or the user can press the minus-sign (-) button, if one is displayed next to the TreeNode. You can also call the TreeNode.Toggle method to alternate between the expanded and collapsed states.

Tree nodes can optionally display check boxes. To display the check boxes, set the CheckBoxes property of the TreeView to true. The Checked property is set to true for tree nodes that are in a checked state.

Note

Setting the TreeNode.Checked property from within the BeforeCheck or AfterCheck event causes the event to be raised multiple times and can result in unexpected behavior. For example, you might set the Checked property in the event handler when you are recursively updating the child nodes so that the user does not have to expand and check each one individually. To prevent the event from being raised multiple times, add logic to your event handler that only executes your recursive code if the Action property of the TreeViewEventArgs is not set to TreeViewAction.Unknown. For an example of how to do this, see the Example section of the AfterCheck or BeforeCheck events.

You can change the appearance of the TreeView control by setting some of its display and style properties. Setting ShowPlusMinus to true displays a plus-sign or minus-sign button next to each TreeNode that can be expanded or collapsed, respectively. Setting the ShowRootLines property to true causes the TreeView to display lines that join all the root tree nodes together. You can display lines that connect child tree nodes to their root node by setting the ShowLines property to true. Setting the HotTracking property to true changes the appearance of the tree node labels as the mouse pointer passes over them. When hot-tracked, the tree node labels take on the appearance of a hyperlink. You can also completely customize the appearance of the TreeView control. To do this, set the DrawMode property to a value other than TreeViewDrawMode.Normal and handle the DrawNode event.

No code example is currently available or this language may not be supported.

The following, more complex code example displays customer information in a TreeView control. The root tree nodes display customer names, and the child tree nodes display the order numbers assigned to each customer. In this example, 1,000 customers are displayed with 15 orders each. The repainting of the TreeView is suppressed by using the BeginUpdate and EndUpdate methods, and a wait Cursor is displayed while the TreeView creates and paints the TreeNode objects. This example requires that you have a Customer object that can hold a collection of Order objects. It also requires that you have a cursor file that is named MyWait.cur in the application directory and that you have created an instance of a TreeView control on a Form.